An assembly line is a manufacturing process in which interchangable parts are added to a product in a sequential manner to create an end product. First introduced by Eli Whitney to create rifles for the U.S. Government[?], the system was later used by Henry Ford to cut manufacturing costs and deliver a cheaper product.

Until the 1800s, craftsmen would create each part of a product individually, and assemble them, making changes in the parts so that they would fit together. With the ideas of division of labour and of engineering tolerance[?], it became possible to create assemblies from parts in a repeatable manner. For larger products, the material would move on a conveyor belt or other conveyance and the workers stayed in place.

This linear assembly process, or assembly line, allowed relatively unskilled laborers to add simple parts to a product. As all the parts were already made, they just had to be assembled. Although there was still a requirement for the craftsmen to create prototypes of the design before mass production, they were no longer required for the actual production. While originally not of the quality found in hand-made units, designs using an assembly line process required less knowledge from the assemblers, and therefore could be created for a lower cost.